Changing Fuel in Cars

[Grin-a-lot]

Righty ho,

I've been running on 95 ron since i've had the car and, more importantly, i had the carbs tuned and jetted with this fuel in it and it was running fine.

The other day I thought it would be good to stick some Superunleaded in (Shell v-power it were) and it promptly ran like a pig, hot, backfiring, bogging down...

Now I had a think and a google about it and there are lots of threads of cars running poorly on 95 ron (where 97 is normally used) but surely it's possible that putting in a fuel that the car isn't expecting, even if it is better quality, could have the same effect?  I've got carbs and advance is set so none of that changed, in fact nothing changed between running on 95 ron and then filling a tank full of 98 ron.  I've since put 95 back in and the car seems to have gone back to normal.  ECUs were the stuff of dreams when my car was built so perhaps the change in fuel content confused it and it couldn't run properly.  If I had the bottle to retune my carbs I would have to see what difference that made but I know i'd c*ck it up so didn't bother.

I'm imagine that I should/could have put 98 ron in first and then got the carbs tuned and I am sure there's an arugment for that but in the short term, does anyone have any experience of putting a higher grade fuel in and it actually making their car run worse?

[peetee]

Hi Darren, I ran 98 RON at Llandow with no noticeable difference? Think it just makes the car run a bit cooler? Maybe better for the engine and generally good practice I was told by the lads at Interpro? Usually runs on 95 standard, but it is fuel injected and ECU/Dynojet/Powercommander. Pete

['The Gaffer']

That is strange, maybe its a timing thing with older non ecu engines??

[paintman]

My Hood is Pinto powered and runs equally well on either.....but i normally put in super when i can get it......funny that, unless it's got water mixed in the tank of fuel at the garage......might pay to give them a phone and see if anyone else is having trouble.

[Grin-a-lot]

maybe its a timing thing with older non ecu engines??

That's pretty much what I was thinking.  There is some talk about changing timing when moving from unleaded to super unleaded so i'm wondering whether that's what it is.

Curious though...

[Hairy Santa]

Righty ho,

I've been running on 95 ron since i've had the car and, more importantly, i had the carbs tuned and jetted with this fuel in it and it was running fine.

The other day I thought it would be good to stick some Superunleaded in (Shell v-power it were) and it promptly ran like a pig, hot, backfiring, bogging down...

Now I had a think and a google about it and there are lots of threads of cars running poorly on 95 ron (where 97 is normally used) but surely it's possible that putting in a fuel that the car isn't expecting, even if it is better quality, could have the same effect?  I've got carbs and advance is set so none of that changed, in fact nothing changed between running on 95 ron and then filling a tank full of 98 ron.  I've since put 95 back in and the car seems to have gone back to normal.  ECUs were the stuff of dreams when my car was built so perhaps the change in fuel content confused it and it couldn't run properly.  If I had the bottle to retune my carbs I would have to see what difference that made but I know i'd c*ck it up so didn't bother.

I'm imagine that I should/could have put 98 ron in first and then got the carbs tuned and I am sure there's an arugment for that but in the short term, does anyone have any experience of putting a higher grade fuel in and it actually making their car run worse?

try a different garage and a different brand name  - Iv'e had this a couple of time s over the years - it does make a difference

[Denzle]

There was talk about this on the VX220 forum and most vxs had the same results as you.  Ran perfect on 95 but terrible on anything higher.  Dont ask me why.....

I run my VX on 95 and think I will stick with it, taking the advice from others.

                                             Denzle...